In the field of electronics, a dielectric material is widely utilized for e.g. a semiconductor, an interposer, a flat panel display, an interlayer insulation film such as a multi-chip module, a bumping for a redistribution layer, a passivation/stress buffer layer or a buildup layer for a printed wiring board. Usually, as a patterning method thereof (a pattern (concavo-convex shape) forming method), dry etching, wet etching, screen printing, inkjet printing or photo-lithography employing photosensitivity of a dielectric material itself may be mentioned.
A material having photosensitivity by itself requires no photoresist which is required at the time of patterning a non-photosensitive material, whereby it is expected to be possible to reduce the number of production steps and improve the productivity by e.g. an improvement in yield. Further, such a material has attracted attention very much since it is thereby possible to reduce the amount of a solvent to be used, thereby to reduce the load to the environment in the process step.
As a heat resistant photosensitive material having photosensitivity, a photosensitive polyimide has been well-known. The photosensitive characteristics are classified into a negative type and a positive type. In the case of a negative type, a photosensitive material is insolubilized at a portion irradiated with light. A soluble portion (non-irradiated portion) is removed by an organic solvent in a developer, followed by heat treatment to obtain a resin film having a pattern formed thereon (for example, see Patent Documents 1 to 4). Further, hereinafter, the resin film having a pattern formed itself is sometimes referred to simply as “pattern”. In the case of a positive type, a portion irradiated with light is solubilized in a developer. As the developer, usually, an aqueous alkali solution is widely used. In the same manner as in the case of a negative type, a soluble portion is removed by a developer, followed by heat treatment to obtain a pattern (For example, see Patent Documents 5 to 8). In various materials other than polyimides, a negative type or positive type photosensitive material has been studied (for example, see Patent Documents 9 to 13, and Non-Patent Documents 1 and 2).
Patent Document 1: JP-B-55-030207
Patent Document 2: JP-B-55-041422
Patent Document 3: JP-A-54-145794
Patent Document 4: JP-A-59-160140
Patent Document 5: JP-A-62-145239
Patent Document 6: U.S. Pat. No. 4,093,461
Patent Document 7: U.S. Pat. No. 4,845,183
Patent Document 8: JP-A-63-096162
Patent Document 9: U.S. Pat. No. 4,339,521
Patent Document 10: JP-A-8-22118
Patent Document 11: Japanese Patent No. 3213001
Patent Document 12: U.S. Pat. No. 6,361,926
Patent Document 13: U.S. Patent application publication No. 2004/76911
Non-Patent Document 1: Polyfile, volume 35 [part 2], page 31 (1998)
Non-Patent Document 2: Polymer Preprints Japan, volume 46 [part 3], page 526 (1997)